An old runner - Tagan EasyCon 480W (TG480-U15)

[SuperStarr]

I have a Tagan EasyCon 480W (TG480-U15) power supply.
Unfortunately‚ (or not - I'm here now! ) it died so I decided to open it and take a look in hope I will find the culprit and give it another try in case I can fix it.
By the way, I'm just a hobbyist, coming from automotive industry (automotive electrician) but as my (limited) knowledge is most of the time obsolete comparing it with latest tech trends, and I don't have experience with AC, most of the time you will find me searching / learning by following the tutorials, reading forums and some e-books, looking videos and so on... I want to learn but I'm not following any program.

As for that Tagan mentioned above, first signs was broken fuse (it exploded) and destroyed Thermistor (https://i.imgur.com/LQSBlIo.jpg ; https://i.imgur.com/1mpkHKI.jpg). As I was lazy enough - I've invested some time just to replace that 2 components and tried to turn it on. Was under impression that Thermistor tired over time and lost the "agility" (didn't even check if that component was in short) so I thought that was that - easy peasy...
Than it happens again - fuse died (exploded) - burnt into dark color and this time even "automatic fuse" (circuit breaker) on that AC line in home reacted and switched off! It was clear that I had to explore it more which I did, additionally.

After some quick (bit this time more serious) inspection, I've found that fuses on Primary are shortened, so there was a short circuit on the Primary, just after filtering unit. At first, I've de-soldered / dismantled a couple of diodes but all of them was good.
After all, when FETs (2SC3320 - NPN power transistors) on Primary was removed, I've found that circuit is not in short anymore but both of that NPN's are in short on all three legs.
So I have decided to order those 2 and replace all the cap's on the Secondary as some of them got "bloated" (bulged, bubbled) and seems like they are not happy anymore . I'm always (trying to) sticking to that electronic proverb: "When in doubt - change it out!"

There is one more 3 leg component - another MOSFET - K2645 - which I checked with "Quick & Dirty MOSFET Test" - and it seems to be OK.

Now, while I'm waiting for replacements to be delivered, I would like to ask you guys, for your opinion:

• What could be the possible reason because they (both) died?
• What could be the cause? Aging? Overloading? Something else?
• Do I have a reason to suspect that they pulled off something else with them?
• In case I have to buy some capacitors - shall I go for "low ESR" ones and if so - why?

In the meantime, if you can imagine from what I've just wrote, level of my (in)experience - do you have any other suggestions for what needs to be checked, reviewed, inspected - if you write a sentence or two - I would really appreciate that!

Looking forward hearing from you!

[Per Hansson]

Re: An old runner - Tagan EasyCon 480W (TG480-U15)

When testing the power supply you should use a dim bulb tester.
Search the forums here for it, bacially just put a incandescent 60w lightbulb in line with the PSU, or replace the fuse with it.
If it's bright when you power up the PSU then it's still shorted but you don't blow stuff up...

As for the reason for the failure: it could be due to bad caps on the primary side.
So I would check the primary side caps with a ESR meter.

As for replacing the bloating Jenpo capacitors on the secondary ideally you should stay close to the original capacitors in the unit now, so the best is to find a datasheet...
Is there some model number printed on the caps?

[momaka]

Re: An old runner - Tagan EasyCon 480W (TG480-U15)

I have pretty much the same PSU, but just rated for different power (lower model I suppose) and under the name ePower. Here is that post:
https://www.badcaps.net/forum/showpo...postcount=2352
So if bad comes to worse and you have blown parts that you can't identify, you can always ask, as I still have this unit.

What could be the possible reason because they (both) died?

Most likely the bad capacitors, as Per mentioned above. PSU was probably oscillating wildly before this happened and something overheated. The suggested action is to replace every electrolytic capacitor in this PSU, save for the two big 200/250V ones on the primary side (as these usually don't go bad... though if your PSU does have Active PFC as the PSU you linked to, those could be bad too.)

In case I have to buy some capacitors - shall I go for "low ESR" ones and if so - why?

Yes, use low-ESR capacitors. The ones specifically made for PSU use will last a lot longer and provide more clean power output.

Generally, the capacitors you should go for is any of these:
Nichicon PW, PS, PM, PJ, and HE*
United Chemicon LXY, LXZ, LXV, KY, KYB, and KZE*
Panasonic FC, FR*, FM*, and FS*
Rubycon YXJ, ZL*, ZLH*

* careful about using these in old PSUs, as they have ESR that is a bit lower than older PSUs may be designed for. Most old PSUs will still work with these (and often without any major adverse effects), but the output ripple could be worse than with the more "entry-level" low ESR caps, such as the ones listed above without the * symbol. With that said, the caps marked with * will be OK for the 5VSB circuit.

In the meantime, if you can imagine from what I've just wrote, level of my (in)experience - do you have any other suggestions for what needs to be checked, reviewed, inspected

Check all of the small components that are connected to the 2SC3320 transistors. In particular, check resistors for open circuit and diodes for short-circuit. Sometimes these can blow when the transistors do, but now always. In addition to that, there should be two small TO-92 -sized transistors on the secondary side near the two small transformers, along with some diodes around them. Check all of these. You may need to remove them from the circuit. Or if you want to try your luck, you can just put the new replacement 2SC3320 transistors in and see if the PSU works. If it does, then obviously those small transistors didn't blow. However, if they blew, the PSU may still appear dead or output only roughly 1/3 to 1/2 voltage or go in "hiccup" mode (i.e. tries to start then shuts down, and then repeats this again.)

When testing the power supply you should use a dim bulb tester.

+1
Excellent advice!

Here is the diagram for that to make it easier to understand:
https://www.badcaps.net/forum/showpo...4&postcount=70
(And note I have the colors for the Live and Neutral wires switched around by mistake... but otherwise, that diagram is accurate.)

As for replacing the bloating Jenpo capacitors on the secondary ideally you should stay close to the original capacitors in the unit now, so the best is to find a datasheet...

The entry level ones I listed above should be fine (those series without the * mark.)
I also think member Pentium4 here recapped (and posted?) one of these PSUs before (after all, he's the one that gave me my unit.) He typically uses Nichicon PW + HE, along with Chemicon KY + KZE and Panasonic FC. So I'm pretty sure this PSU will take those caps fine. But if you want a reference, my ePower PSU I linked to above has mostly Fuhjyyu TMR caps on the output rails, along with Fuhjyyu TNR - both of which are somewhere between GP and entry-level low ESR (IIRC).

[MHTSOS]

Re: An old runner - Tagan EasyCon 480W (TG480-U15)

I have repaired 2 of these PSUs both with blown primary drivers. On both of them the pramary caps were dead so I would start there. You will need at least an ESR meter for this kind of repair. Also check the 2 caps that are connected to the bases of the primary drivers. They should be 50V and 1uf to 10uf I don't remember atm. Judging by the age of the PSU if they are not dead by now they are definitely dying. If the dry up the PSU will work with no load but will shut down as sosn as you try to draw a few watts

[momaka]

Re: An old runner - Tagan EasyCon 480W (TG480-U15)

I have repaired 2 of these PSUs both with blown primary drivers. On both of them the pramary caps were dead so I would start there.

Ah, I suspected that might be the case as well when I saw this PSU has Active PFC. I suppose I'm lucky that mine (ePower EP-350XP-24) doesn't. APFC tends to kill cheaper brand caps... and sometimes even Japanese brands if the manufacturer cheaped out and used 400V or 420V caps with smaller capacity instead of larger caps rated for 450V.

Since this PSU uses half-bridge topology, I bet those primary caps are either 200V or 250V units. (But please verify!) Whichever the case, use 250V only, if you intend to keep APFC function. And the caps should be a good Japanese brand too. Same or one level higher capacity, too, if possible.

-OR-

Get rid of the APFC circuit. It's just extra heat/inefficiency that these PSUs simply don't need. There's no benefit from it, other than universal line voltage. But you guys are in Europe with 220/230 lines, so that won't be an issue. As I said, my ePower doesn't have that APFC circuit and like many of my other non-APFC PSUs, it probably will last much longer because of that.

[MHTSOS]

Re: An old runner - Tagan EasyCon 480W (TG480-U15)

APFC tends to kill cheaper brand caps... and sometimes even Japanese brands if the manufacturer cheaped out and used 400V or 420V caps with smaller capacity instead of larger caps rated for 450V.

The only reason I can think of that they use 400V caps instead of 450V is planned obsolescence. I mean they know damn well that APFC is going to kill them eventually but it is a good way to keep the money rolling.